88 EXPERIMENT STATION EECORD. 



The progressive formation of soluble nitrogenous products by 

 galactase, trypsin, and panereatin differentiated these enzyms from 

 pepsin and rennin, digestion with the latter enzyms and with commer- 

 cial rennet extract taking place only in milk acidified with 0,2 per 

 cent hydrochloric acid. The action of Bacillus subtilis, JB. 299, and 

 B. 83 as regards the conversion of nitrogen into soluble form was 

 similar to that of galactase. The amount of soluble nitrogen was not 

 increased by B. acldi lactici or B. coll communis. Proteolytic 

 changes in all cases were more rapid in the earlier than in the later 

 stages of digestion, from 30 to 85 per cent of the total nitrogen being 

 digested during the first 7 days. A difierentiation of the proteolytic 

 ferments was also shown by the character of the decomposition prod- 

 ucts. No ammonia was produced by trypsin, panereatin, and pep- 

 sin. In samples of milk acted upon by galactase. Bacillus sitbtilis, B. 

 299, and B. 83 for 112 days the nitrogen in the form of ammonia was 

 respectively 0.04, 0.21, 0.11, and 0.15 per cent. In cheese 120 days 

 old the ammonia was 0.17 per cent. Tryptic digestion was more 

 rapid than that of galactase. The absence therefore of ammonia, 

 together with the total disappearance of albumoses, and the presence 

 of large quantities of amids and peptones in digestion with trypsin, 

 and the presence of both ammonia and albumoses in digestion with 

 galactase at the end of 112 days strengthened the conclusion that these 

 two enzyms are not identical, although allied in some of their proper- 

 ties. The relative quantities of different end products of digestion, 

 especially amids and ammonia, differentiated galactase from the bac- 

 terial enzyms. 



The relation of galactase to other enzyms is considered in connec- 

 tion with the cause of the changes taking place in the ripening of 

 cheese. " The similarity of products formed in the normal ripening 

 of Cheddar cheese with those produced by galactase where all other 

 factors are controlled, shows beyond all question that the main causal 

 agent in the proteolytic changes that occur in these cheeses is due to 

 this enzym." 



Influence of galactase in the ripening of cottage cheese, S. M. 

 Babcock, II. L, Russell, and A. Vivian ( W!sco)isl)i St<(. Rpt. 1899, 

 P2>' 175-178). — Several experiments were made in a study of this ques- 

 tion. In 2 experiments cottage cheese was made from normal milk, 

 the acid being developed naturally by bacterial fermentation. In 1 

 of the experiments the curd was washed with warm water to remove 

 as much acid as possible. In 2 other experiments cottage cheese was 

 made from milk which had been heated to 192° F. for 20 minutes in order 

 to destro}'^ the inhei'cnt galactase. The acid was developed in one case 

 by means of a buttermilk starter and in the other 0.5 per cent of com- 

 mercial lactic acid was added. In each of the 1 experiments one por- 

 tion of the curd was kept under chloroform. Determinations of the 



